CHT and Oxygen Sensor Learnings
 

I am chancing down a surging idle issue on my '87 911 as being tracked here. I just changed the CHT and Oxygen sensors last night with the help of Wayne's book and I figured I would note a few learnings that aren't covered in the book.

Oxygen sensor replacement on an '87: Jack up the car and remove the left-hand, rear tire (use a jack stand and place the wheel under the car for additional safety). Remove the cat heat shield so that you can access the sensor. My car has a shield around the oxygen sensor. There is a simple clip on this shield that clips onto the oxygen sensor itself. You can simply unclip this sensor by pulling on it (in the direction opposite of the sensor). After that Wayne's book does a great job covering the remaining steps.

CHT sensor replacement on an '87: There are a lot of great writeups on how to do this on this forum. I think the three things I can add are 1. Remove the ducting that is attached to the heater blower in the engine compartment for better access. 2. If you are going to change the CHT, consider also replacing the speed and reference sensors if the rubber coating is falling off these. 3. Before you pull out the old CHT sensor, tie a string to it to thread the new sensor up into the engine compartment.

This forum has provided so much knowledge, hopefully this can help someone too.

Can we assume these parts did not make a difference?

Yes. Click the "here" link above to track my progress.